Classifications

• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
  • G01M1/00—Testing static or dynamic balance of machines or structures
  • G01M1/14—Determining imbalance
  • G01M1/16—Determining imbalance by oscillating or rotating the body to be tested
  • G01M1/22—Determining imbalance by oscillating or rotating the body to be tested and converting vibrations due to imbalance into electric variables
  • G01M1/225—Determining imbalance by oscillating or rotating the body to be tested and converting vibrations due to imbalance into electric variables for vehicle wheels
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
  • G01M1/00—Testing static or dynamic balance of machines or structures
  • G01M1/02—Details of balancing machines or devices
  • G01M1/04—Adaptation of bearing support assemblies for receiving the body to be tested
  • G01M1/045—Adaptation of bearing support assemblies for receiving the body to be tested the body being a vehicle wheel
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
  • G01M1/00—Testing static or dynamic balance of machines or structures
  • G01M1/30—Compensating imbalance
  • G01M1/34—Compensating imbalance by removing material from the body to be tested, e.g. from the tread of tyres
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
  • B23B—TURNING; BORING
  • B23B2215/00—Details of workpieces
  • B23B2215/08—Automobile wheels

Definitions

• TITLE "Method and equipment for the dynamic balancing of the rims of wheels of motor vehicles"
• the invention relates to a process and equipment for the dynamic balancing, during the production cycle, of the rims, particularly light alloy rims for the wheels of motor vehicles, or for the dynamic balancing of other parts having similar requirements.
• rims are subjected to final machining on numerically controlled machine tools, which turn them and finish their surfaces and which make holes for the passage of bolts for subsequent fixing to the motor vehicle and the perimetric hole for the passage of the future wheel inflation valve.
• the rim On the machine tools, the rim is mounted in two different positions, so that it has first one of its faces and then the other facing upwards, for example.
• the rim is placed on a balancing machine, which has the function of indicating and determining quantitatively in which area or areas of the round angle, which are marked visibly, material has to be removed from the rim to dynamically balance it.
• the rim is mounted on another machine tool which removes the material from the said areas identified by the balancing machine, and this operation is usually carried out with milling or piercing operations, frequently in areas of the rim which are not visible, for example on the inner side, or possibly by localized turning operations, for which the rim is normally made to rotate in an eccentric position.
• the balancing machining of the rims must be very precise. At the present time, for example, tolerances of approximately 14 g/mm are permitted on the vibration vector, as against the former tolerances of approximately 70 g/mm, in order to provide greater safety for users, even at the higher speeds which rubber-tyred wheels of motor vehicles can reach at present.
• the invention is intended to overcome all these drawbacks of the known art with the following proposed solution.
• the whole process of checking and executing the balancing of the rim is carried out by the numerically controlled machine tool which also carried out the final step of final machining of the said rim, with the evident major financial advantages derived from this condition.
• the said finishing machine tool is provided with sensors for detecting the vibrations produced on the mandrel by the imbalance of the rim.
• the mandrel which carries the rim is driven in the usual way by a motor with electronic speed and phase control.
• the rim is positioned with the valve hole in a predetermined angular position which is known to the logic circuit, which, by means of the said sensors, determines the angular position and the extent of the dynamic imbalance, and the final balancing machining is carried out by eccentric and/or localized turning, with the rim continuing to rotate normally about its axis, at the correct velocity, while the turning tool is moved by the numerical control system in such a way as to remove the quantified amount of material only in the area or areas identified by means of the said sensors.
• FIG. 1 is a lateral elevation of a rim of the type in question, and shows a possible eccentric turning operation carried out to achieve the dynamic balancing of the said rim;
• Figure 3 shows a flow chart of the balancing function of the machine.
• the letter M indicates the mandrel of the numerically controlled finishing machine tool, whose shaft 1 is supported rotatably by bearings 2 and is driven by a motor 3 with electronic speed and phase control, for example a brushless motor, with brake.
• the number 4 indicates the platform of the mandrel, having an axial pin 5 which interacts, for the purposes of centring, with the axial hole of the rim C, the said platform being provided with perimetric self-centring brackets 6 which secure the said rim C.
• the number 7 indicates the electronic numerical control unit which interfaces with a programming and interrogation system 8, with the mandrel drive motor 3 and with the system of machining tools 9 which are mounted, for example, on a revolver unit positioned on means 10 for movement along at least two orthogonal axes, motorized to carry out not only turning operations but also other operations such as drilling.
• the finishing machine tool is provided with one or more sensors 11 , of the accelerometer type for example, for detecting the radial vibrations and possibly also axial vibrations of the shaft 1 of the mandrel M, for example the vibrations generated by this shaft in the outer ring of at least one of its support bearings 2.
• sensors 11 of the accelerometer type for example, for detecting the radial vibrations and possibly also axial vibrations of the shaft 1 of the mandrel M, for example the vibrations generated by this shaft in the outer ring of at least one of its support bearings 2.
• the location of the sensors shown in Figure 1 is shown purely by way of example and is not restrictive. If a plurality of sensors is used, they can for example be spaced apart angularly at intervals of ninety degrees.
• the electrical signals produced by the sensors 11 are sent to an amplification, calculation and processing unit 12 which interfaces with the numerical control unit 7 and with the aforementioned operating logic, and which can be programmed and 10360/E
• the final machining of the rim is normally carried out in two successive steps, for example in a first step in which the inner face of the said rim is machined, and a second step in which the outer face is machined, with the formation of the fixing holes FF and the valve hole FV of the rim.
• the outer lateral surface of the rim, on which the tyre is to be placed is also finished.
• the machine which has carried this out automatically proceeds to the step of balancing the finished rim, as indicated henceforth with reference to the flow chart in Figure 3, the said rim being kept with its outer face orientated upwards.
• the scope of the invention also includes the variant in which, on completion of the final machining of the rim, the said rim is repositioned on the mandrel M with its inner face directed upwards, in such a way that the aforesaid eccentric turning operations are carried out on the inner face of the rim, with the advantage of being executable with a limited degree of finishing, since they are not visible from the outside.
• automatic manipulation means (not shown) are provided, these means positioning the rim on the mandrel M of the machine tool with the area intended for the valve hole FV in a constant and predetermined position which is known to the unit 7 and/or 12.
• the said units can also be provided with information, for example by means of the programming unit 8, about the dimensional characteristics and the eccentric position of the hole FV, so that the system can discriminate the size and the position in the round angle of the vibrations caused by the said hole FV.
• step 13 shows the start of the balancing.
• step 14 shows the checking and quantification, by the unit 12 of Figure 1 , of the vibrations produced by the mandrel M carrying the rim C to be balanced, with allowance for the vibrations caused by the valve hole FV, which will later be substantially compensated by the inflation valve which will 10360/E
• Step 15 shows the determination of the actual values and coordinates of the dynamic imbalance of the rim, by means of the unit 12 which executes an operation of subtracting the vibrations produced with the mandrel unloaded from the vibrations deduced in step 14 (see below).
• Step 16 shows the execution of the eccentric and/or localized turning operation by the machine tool, for carrying out the dynamic balancing of the rim to the predetermined tolerances.
• the rim is made to rotate about its axis at a predetermined velocity, in the region of 400-700 rpm, for example approximately 500 rpm, while the unit 12 orders the numeric controller 7 to control the predetermined tools 9 in such a way that they carry out a turning operation on a predetermined area 17, which is usually eccentric, on any suitable part of the surface of the rim, for example on the strongest lateral part on which the tyre will be fitted (Figs 1 and 2).
• the turning 17 can be carried out with a good level of finishing and can be integrated harmoniously into the external appearance of the rim, in such a way that it would not be significantly visible to the naked eye, even if, by contrast with the previous suggestion, it were carried out on the visible face of the rim.
• the areas on which the eccentric turning operation or operations are carried out are to be selected in advance in a suitable step in which the system is programmed.
• Step 16 is followed by step 18 which checks whether or not the balancing has been carried out correctly. If the result is negative, the values of the residual imbalance are identified and quantified, and, as indicated by the path 19 in Figure 3, a return is made to step 16 for another eccentric turning operation. However, if the rim is found to be correctly balanced, step 18 is followed by step 20 which constitutes the end of the balancing and the removal of the finished and balanced rim from the mandrel M of the machine.
• Step 20 is followed by step 21 in which the unloaded imbalance of the mandrel M is checked and quantified, this value being used as indicated by the path 22 in the 10360/E

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• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Testing Of Balance (AREA)

Applications Claiming Priority (2)

Publications (1)

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ID=34113415

Family Applications (1)

Country Status (3)

Families Citing this family (6)

Family Cites Families (8)

• 2003
  • 2003-07-29 IT IT000448A patent/ITBO20030448A1/it unknown
• 2004
  • 2004-07-14 WO PCT/EP2004/051492 patent/WO2005012867A1/en active Application Filing
  • 2004-07-14 EP EP04766222A patent/EP1656540A1/de not_active Withdrawn

Non-Patent Citations (1)

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